Putorescent tube



M. SCHMIERER FLUORESCENT TUBE June 24, 1930. Re. 17,712

Original Filed Feb. 27, 1914 4 sheets-SM 2 iIif/masas': Even/01':

M. SCHMIERER June 24; 1930.

FLUORESCENT TUBE 4 Sheets-Sheet 5 Original Filed Feb. 27, 1914 ll l'lzzess es (5M /Pdz I June. 24, 1930. SCHM'ERER LUBE FLUORQS CENT 01 iginal -Filed Feb. 27, 1914 4 ts-Sheet J12 we for:

Rama-1...... 24, 1030 U ITED srATES PATENT OFFICE IIOHEL SGHHIEREB, OF BERLIN-LICHTERFE'LDE, GERMANY, ASSIGNOR '10 RADIO PAT- I EN'I'S CORPORATION, OF NEW YORK, N. Y., ACORPORATION OF NEW YORK FLUORESCENT TUBE Original 1T0. 1,595,735, dated AugustllO, 1926, Seria1No.821,809, filed February 27, 1914, and in Germany larch 5, 1913'. Application for reissue filed October a, 1927. Serial no. 224,509;

This invention relates to systems and apparatus. for electrically producing images employing gaseous conduction devices, par-" ticularly, to so-called .fluorescent tubes or glow lamps. I I

More especially it relates to means for transmitting pictures by electricity, but may also be used for other purposes, for example,

for indicating the direction of a current in Rontgen ray and the like. Y N

All arrangements for transmitting pictures 'over great distances are based on the principle, that the picture to be transmitted at the transmitting station is divided into luminous points, the intensities of which are converted into changes in an electric current and are transmitted either simultaneously or successively (by means of alternating currents of different frequency), .While at the receiving station the reverse process occurs, the incoming current impulses being reconverted into luminous points of corresponding intensity, which are then assembled to form a picture. At the receiving station there must therefore be an arrangement which allows of converting changes'in an electric current into changes in the intensity of light. Of the devices which have been suggested for this purpose, electric fluorescent tubes aflord the advantages of plans, for advertising purposes consuming very little energy, of the color of the light radiated being unchangeable and, above all, of the'absolute absence of inertia. Furtherinore "they require little space, are proof against vibrations and may be produced at a moderate cost. Hitherto they were only employed in form of socalled Geissler tubes, namely, tubes which have been evacuated to a comparatively high degree, the whole space in which will fluoresce when a current passes between the electrodes. These Geissler tubes have only a small intensity, so that it requires a comaratively long exposure to sufficiently afect the sensitive emulsion. A further disadvantage of the Geissler tubes is this, that a picture which has been received by their aid is composed of light and dark superficial elements. Such a picture cannot however,

plate without need of a screen. purpose the device which converts the curlike a photograph, be directly reproduced by any printing method, and would first I have to be divided by a line screen by copying 1t through suchon to a zinc plate covered with chromo-gelatine, so as to produce a printing block which may be used after the known half tone method. A half tone picture consists, as generally known, of large and small points scattered in a chessboard manner over the surface of the picture. By the different size of these points the various shades are produced. The larger the points at one part of the picture, the darker this part will appear, if the picture is observed ata, sufficient distance, so that the individual points can not be distinguished. For practical reasons it is however, impossible to copy a picture, which has been divided up into superficial elements a second time through a screen if the latter is not so fine that a large number of points come on each of the said superficial elements. The

number of the screen is, however, by no transmitted are considered as sufiicient, the

superficial element" would be 1 square millimeter. It would be impossible to reproduce finer details of a picture. It therefore appears advisable to produce the pictures transmitted directly in a half tone manner, so that they may be copied on to the zinc For this rent changes into light changes must produce not only light spots of even size and different intensity but alsoc-lifl'erent size as well. the fluorescent tube hereinafter described, which also meets the second requirement, namely of producing a more intense light than a common Geissler tube. The size of the luminous spots produced by this tube, on a current passing through it, is in direct proportion to the intensity of the current.

This object is obtained by means of In the accompanying drawings:

Fig. 1 is a front elevation of the tube.

Fig. 2 is a horizontal section.

Figs. 3 and 4 show a combination of a plurality of tubes to a panel of tubes, Fig. 3 being an elevation, Fig 1a horizontal section.

Figs. 5 to 7 exemplify systems for trans mitting images. Fig. 5 shows a direct connection. Fig. 6 shows an indirect connection, a single selenium cell being used at the transmitter and a single fluorescence tube at the receiver, and Fig. 7 the indirect connection with a plurality of selenium cells and fluorescence tubes respectively.

Fig. 8 is an elevational view of an altermstive iorm urglcw lamp or fluorescent tube having a spiral anode.

In Figs. 1 and 2 a and b are the two electrodes of the fluorescent tube. The electrode a is a perforated plate, a grating, a netting or the like, made of metal, preferably of aluminum. It may also consist of aspirally wound wire or strip of sheet metal such as shown in Fig. 8. 'Itis, however, preferable to make it of one solid piece, by drilling holes of even diameter at an even and as small as possible pitch into a metal plate. The hexagonal shape of the late shown in the drawing allows of a goo utilization of the space with comparatively large strength and comparatively easy working. Any other arrangement of the holes with the same size and number of'holes per superficial unit, would result in a smaller thickness of the webs between the individual holes and thus render the making of the electrode more diflicult. Otherwise the arrangement of the holes is immaterial with regard to the subdivision of the picture to be transmitted into superficial elements.

The electrode 6, which is likewise preferably made of aluminum, is much smaller than the electrode a, and, seen from the observer, it is arranged behind the same;

The tube is filled with an inert gas, preferably nitrogen and evacuated until the gas pressure amounts to only a few millimeters mercury column. If one of the rare gases,

such as helium or neon is used for filling the tube, the current consumption "will be considerably lower. The radiated light is, however, poor in actinic rays, so that no material advantage would be derived therefrom if the tube is to be used for tele-photo graphic purposes. poses, luminous advertising signs and the like such a filling would, however, be of advantage. When a current is sent through the tube the two electrodes will luminesce,. the electrode connected to the negative pole] of the source of current being of the higher intensity. The luminosity at the pole is practically negli 'ble. For t is reason the luminous elec which will require a higher pressure.

For tale-optical put-- OSltiVe e a should, in most" cases, be made the cathode. The radiated light in this case will consist of a rather clearly defined, almost circular illuminated spot if-the anode b is a rotation body, the axis of which is vertical to the plane of the cathode, thus, for example disc, ball, cylinder, cone, truncated cone or the like. The spherical shape indicated in the drawing has the advantage that in case the stem of the electride should be fused in obliquely this will not affect the effectiveness of the tube, as the effective part of the anode 6, turned towards the cathode a will, in all cases, be a hemisphere. l lowever, the distance between the two electrodes must be somewhat greater than would be the case if the electrode 2; were to terminate in a poiiitt, the electrode 6 is a polygonal body, thus either a prism, pyramid, truncated pyramid, star or the like the tube will, on-the passage of a current, show the tendency to produce a polygonal luminous spot instead of a round one. When a four-cornered electrode 11 is used, especially a four point star, there will be produced at low current an almost circular luminous spot, at medium current an almost square, luminous spot, and at a high current a star shaped luminous spot will be obtained. This fully corresponds with the conditions of a half tone, in'which small points are round, medium points square and large points starshaped. If the electrode 6, lastly. has on the side turned towards the electrode a several proiecting parts, or if there are several electrodes conductively connected with each other, as many luminous spots will, on the passage of a current be produced, as there are projecting parts or electrodes 5. The outlines of the individual luminous spots will then, of course, correspond to the shape of the electrode b. trodes b is then preferable, when the pic ture received shall be of a finer ruling than 'the picture transmitted.

'The radiation is the most intense within the holes'in electrode a. If the radiation is, to be limited to the face of the "electrode and the space in the holes, the electrode may, on its reverse side, he covered with an insulating material, for example a coat of varnish. The luminous intensity of vthe fluorescent tube increases with the decreasing of the sectional area of theholes. It is, therefore,

in most instances preferable to make the size of the holes as small as possible, as the kindand the pressure of thegas allows. The higher the gas pressure, the smaller the size of the hole may be,,as the thickness The use of such subdivided elecof the dark layer covering the cathode, which is necessary for producing the fluorescence decreases with the gas pressure. As the gas pressure in tubes in use decreases in time,

as shown by experience, and the thickness of the dark layer thus increases, the size of the openings should be chosen so that the development of the dark layer, even after long use, will not be prevented by the opposite inside walls of the holes.

The luminosity of the tube is further in proportion'to the thickness of the electrode plates, or to the thickness of the electrode a respectively. The best results are obtained with electrodes, which are made of 3 millimeter plate.

For the purposes of the slower tele-photography for instance by aid of such processes in which one single selenium cell is used in the transmitter for converting the intensity of the individual elements of the picture into corresponding current changes, prefer ably also one single fluorescent tube is used in the receiver for I'B-COIIVBItlDg the current -changes into corresponding light changes.

In doing so an arrangement must be made,

i by which the rays of light radiating from film will receive a corresponding movement.

Also both tube and film may be stationary and the rays emanating from the tube may be directed by suitable optical means, such as a revolving or an oscillating mirror'to the part of the sensitive film COIIGSPOIldiIlg to the respective acting part of the picture being transmitted. Or the rays may be allowed to ass throu h corres aondin 'l b h a shaped hole or slit shutters onto such parts only. It may also be possible to combine any or several of these methods.

For tele-visual purposes and for rapid tele-photography, for instance such methods, in which a plurality of selenium cells are employed in the transmitter, also'these' tubes are preferably employed in a larger number. With a method, in which the sev-- eral cells are arranged on a panel in such a manner, that they preferably form parallel lines at right angles to each other and at an even pitch, the tubes are preferably arranged in the receiver of the same number and according to the same plan. Then one selenium cell and one fluorescent tube each will correspond to each luminous point of the picture or image. These may either by aid of alternating currents of different frequency transmit the intensities of the indielectrodes B connected.

vidual luminous points simultaneously, or they may-be successively connected by means of synchronous commutators into the same circuit. The stronger the selenium cell is lighted, the brighter thus the luminous point, the larger and brighter will be the lighted spot on the platen of the corresponding fluorescent tube, so that the panel of fluorescent tubes reproduces the picture transmitted with its accurate gradations of light. Such apanel of fluorescent tubes may be greatly simplified in its arrangement, by combining according to Fig. 3 (elevation) and Fig. 4 (horizontal section) the tubes of each row with each other to a multiple tube 1, in which the electrodes a are fused to' one single strip-shaped electrode A, behind which the other pole electrodes B are arranged at even pitch, one for each luminous point. Of course also here subdivided electrodes B may be employed, when the received picture shall have a finer ruling than the picture transmitted. Itis rather immaterial .as regards the operation of the tube, which shape and arrangement of the holes in the electrode Aare employed, and here the same remarks apply as to the single electrode a of the single tube. If the electrodes A are made of one single strip of sheet met-a1, the same may be continuously perforated as this is indicated .in. the uppermost electrode in Fig. 3, or,-a star of holes may be provided for each of the electrodes B, as it is shown in the second electrode A. The commutation of such a tube panel may be performed in either of two ways. Either, all electrodes A are connected parallel and the electrodes 13' are connected singly with the sections of a commuta-tor, in which case a luminous spot is produced at that part of the panel only, which corresponds to the electrode B. which, for the moment is connected through the commutator; or, the wires leading from each row of the electrodes B, at right angles to the electrodes A, are connected with wires 5 (Figs. 3- and 4) and the electrodes A and the rows of electrodes B are commutated sepa rately. In this latter case a luminous spot is produced only at such point where the connected electrode A crosses the row of This method of commutation is illustrated in Fig. 7 wherein the picture or image to be transmitted is projected by a suitable optical arrangement on the bank'of cells-"S. By means of commutators K and K at the transmitting station and commutators k and k at the receiving station of each cell corresponding to a point ,on the image is successively connected in circuit with correspondingly situated sets of the electrodes AB in the receiver the receiving lamp being thus lighted point by point in succession. It will be understood that the commutators will be rotated with suflicient velocity so that the complete eye or in about i of a second. Preferably, and for facilitating theevacuation, and se curing a uniform gas-pressure allymulti' ple tubes, the individual tubesofithe panel,- are connected by means of short interme-;

image is completely scanned and reproduced within the retentivity period of'the human diate tubes, or fused by means of short tubes 2 to a. transverse tube 3. This objectmay also be obtained by the totalityof the elec-.

trodes A and B being arranged Within a common glass vessel, and, for further simmitter.

mitter. cally exemplified .in Fig. 5 for a plant in plification, all electrodes A may be fused to .one large plate, or, the electrodes B may be conductively connected with each other in rows, whereby fused joints may be saved.

In the latter case the saving in fused'joints will be greater,'but in the former case the advantage is derived, that luminous spots may be produced, the diameter ofwhich is larger than thedistance between the electrodes B, whereby a larger richness-in contrasts of the picture received maybe obtained. The glass wall closing the receiving vessel at the front, must be convex, so as to be able to bear the pressure of the atmos-f phere.

A panel of fluorescent tubes may, of course also be employed with such plants for picture telegraphy, in which there is only one single photo-electric element (selenium cell or the like) in the trans- Vice versa it is also possible to employ with a plant comprisinga plurality of photo-electric elements, at the receiving gradually the whole surface of such film is.

covered, as this has been described with reference to the single tube. Generally it'is, however, preferable, to employ the same principle at both stations, thus the same number of tubes, or electrodes B, as there aresensitive to light elements. This alffords the advantage, thatthe whole plant is simpler and that the same driving mechanism may be used for both stations.-

For feeding such fluorescent tubes a'current of a few hundred volts only is sufficient. The. intensity of the current is extremely small, so that it is possible to connect them directly in series with the light sensitive element or elements of the trans- This connection 1s diagrammati which at-thetransmitter the picture to be transmitted iswrapped inform-of a film on a revolving and axially advancing glass drum T, while at the receiverthe sensitive .t is the transformer.

film is likewise wrapped on a drum T, which has a synchronous" movement. In such arrangements generally one single photo-electric element is employed in the face of the pictureto betransmitted, whereupon, after it has been reduced according to the intensity of this point, it fallsonto the selenium "cell's. Sometimes with such arrangements the conversion of the intensities into current fluctuations is also obtained by the picture to be transmitted being. applied to the drum, not in form of a film but of a chromo-gelati-ne plate or also a half tone on a metallic foil, anda feeler which successivelycovers the whole surface sends either directly by electric means (under utilization of the variable conductivity of the chromo-gelatine'fih'n) or by mechanical means (under utilization of .the different heights of the film) currents corresponding to the intensities into the transmission line. The receiving, arrangement remains, how ever, the same. E is the source of current. At the receiver 0 is the lens, which produces the image of the luminous spot produced on the electrode 'a on the sensitive film, which is laid around the drum T. It is, however, for

practical use, not advisable to connect the fluorescent tube directly into the transmission line. It would have the disadvantage that the transmitter would be greatly endangered by a possible short-circuit in the transmission line. Furtherinore such direct connection has the disadvantage, that the fluctuation of the total resistance in the circuit, thus also the changes in the intensity of the current are not, proportional to the transmitter and one single light. regulating .element at the receiver; In Fig. 5 O is the vlens ,through which the light of the lamp .L. is concentrated in one point on the sur-' changes inthe resistance of the photo-electric element, as the invariable resistance in the transmissionline and the not greatly varying resistance of the fluorescent tube adds to the resistance of the light, sensitive ele ment. For this'reason an-indirect connection is to be preferred, in Whichthe current is transformed to a higher voltage. ig. 6'

illustrates such connection for the receiver of a plant, the'transmitter of which corresponds to Fig. 5. U is: the interruptor, which isnsed'toconvert the transmitter current into an intermittent direct current, as the-direct current derived from the battery Bcannot be transformed! The interruptor might also be arranged atthetransmitter station, If, instead of the battery E a souree of alternating current is em; ployed the interruptor is not necessary.

ther advantage, that the fluctuations of the Also this transformer may be arranged at the transmitter. This current in thetransmission line, thus also in the fluorescent tube are almost proportional to the changes in the resistance of the photo-electric element, as the resistance in the primary winding of the transformer is very low compared to the resistance of the transmitter, while the resistance in the transmission line is considerably greater. It

is the best, to employ adouble transformation, and to provide a transformer both at the receiving and at the transmitting stations. This affords the; further advantage of a low voltage in the transmission line.

For reason of a may be provided in the receiver. If the selenium cells are arranged in such a manner,

that they are influenced by luminous points axially adjoining each other, in which case the axial travel of the drums must be accordingly faster, it is {possible to employ in the receiver instead yof several tubes one single multiple tube of the kind shown: in j F igs. 3 and 4, one single lens 0 reproducing,

all luminous points as luminous points lying axially next to each other on the photosensitive film.

Also when the selenium cells are arranged in such a manner, that they are influenced by points at greater distances from eagh other, it is possible to employ a multiple tube, onl then the distance between the electrodes must be'made accordingly greater. The lat-' ter arrangement has the disadvantage, that .for each of the selenium cells and for each of the electrodes B a separate lens must be provided. 7

In case one single tube is used, or a mat-ls tiple tube, it is advisable, for producing greater contrasts in the received picture, to

make the dimensions such, that the images of the luminous spots on the photo-sensitive film will, at highly illuminated selenium cells be largerthan the distance between the neighbouring luminous points of the received picture. Then the images will more or less overlap with their edges, so that only very small dark points will remain between them.

Fig. 7 illustrates an indirect connection in the case of an arrangement, with which a larger number of selenium cells 8 are employed in the form of a panel in the transmitter. The individual cells are preferably connected successively by means of two commutators K and K: into the circuit, of which commutators the one connects the cells in rows, and the other, revolving at a higher speed, connects the cells ofeach row. In the receiver the electrodes A and B of the panel of fluorescent tubes are connected in a similar manner by means of two synchronously revolving commutators K- and k m the same series. The commutator, revolving at the higher speed, of thetransmitter may also, at the 'sametime, serve as interruption Instead of the panel of tubes one single multiple tube may be employed, which is moved in the plane of the panel, or with which a relative corresponding movement between the images of the luminous spots and the photo-sensitive film after one of the methods described hereinbefore with reference to the single tube is produced. Otherwise the same applies here as has been said with reference to the Figures 5 and 6.. Of course the transmitter according to Fig. 7 may also be used in combination with thereceiver according to Fig. 5 and vice versa the receiver according to Fig. 7 may be used with the .transmitter according to Fig. 5, provided an intermittent direct current oran alternating current is employed.

In all instances, where several selenium cells or fluorescent tubes are employed, it is [also possible instead of the successive con-I nection, to operate simultaneously, if sev eral transmission lines are available, or, if only one such transmission line is available,

alternating currents of different frequencies" are employed, each tube selecting its corresponding current by tuned resonance circuit. 1

, With such fluorescent tubes the sensitiveness -may be regulated, besides the regulation of the gas pressure which comes less" into question for practical use by varying the step of-the transformers, and by adding resistances or by superimposing a direct or an alternating voltage. By the latter it is possible to convert the alternating current supplied by the transformers into intermittent direct current, or, into an unsymmetric a correspondingly alternating current, the maximum value of the positive momentary pressuresof which may optionally be larger or smaller than the maximum of the negative momentary pressures and vice versa. The regulation is preferably effected in such a manner, that when the selenium cell is not-illuminated, the-tube 1s but slightly luminescent, .and when the cell is strongly illuminated a luminous spot it produced,- the maximum' diameter of which is about 1% times as great as the distance between the electrodes, or the image of which is, at the same rate, larger than the distance between neighbouring points of the picture received. Then the latter will, as

regards appearance half tone, there are always still small dark points in the highest lights, and small light points in fully correspond to a the deepest shadows.

If the transmitting current is increased by a quantitative relay with variablecurrent lncreasing factor, the regulation of the in which, for practical reasons sensitiveness of the fluorescent tube may also posite one of said cathodes and adapted'to be effected by varying the rate of the relay, or by employing a variable shunt connected parallel to the relay.

I claim: i

1. The combination in a glow lamp, ofa plurality of anodes and a plurality of cathodes, said anodes and cathodes being arranged in cooperative relation and disposed in coordinate rows.

cooperate therewith;

4. The combination in a glow lamp of a arallel catho es each consist- 9;In combination, a glow discharge lamp comprisinga continuous electrode, a plurality of spaced electrodes arran ed in a row parallelto said continuous e ectrode, and means leadin for conducting a potential causing a discharge between any one of said spaced electrodes and a corresponding portion of said continuous electrode."

' MICHEL SCHMIERER.

pair of spaced cooperating electrodes, one u of said electrodes being perforated, the

other of said electrodes being disposed insuch relation to the erforated portion of the perforated electro e that a luminescent phenomenon occurs within the perforation! 5. The combination in a glow lamp of a perforated electrode element and a second electrode element disposed in spaced relation to said first electrode element, circuit connecable potential being applied between said electrode elements,aluminous discharge is tion terminals for said electrode elements, the arrangement being such that upon a suit produced in and about the perforated portion of said first electrode, said luminous discharge being visible from the side of said first electrode opposite the other of said electrodes.

6. The combination in a glow lamp of a plate forming an electrode, said plate having a plurality of separated areas, each of which is perforated and a plurality of additional 'j' electrodes each of which is individuallydisposed in'spaced relation to' one of said perforated areas. I

7 In combination, a glow discharge lamp comprising a plurality of spaced electrodes in row-formation, a single electrode adapted to cooperate with said spaced. electrodes,

and lead in means for conducting a potential producing a discharge between said com mon electrode and each of said first mentioned electrodes in succession. a

8. In combination, a glow discharge lamp comprising a plurality of spaced electrodes arranged in parallel rows, a continuous electrode for each row of spaced electrodes, and lead in means for conducting a potential producing a discharge between each common electrode and each of the associated spaced electrodes in succession. 

